This invention relates to a technique for recording and reproducing compressed, time division multiplexed video and audio data on, for example, optical disc.
Disc-shaped recording media have come into widespread use for recording speech, video information and computer data. For example, the CD-ROM is used to record speech data, video data and other computer-usable data for use in a computer system. Files that are used for accessing the recording medium exhibit an advanced file classification storage function, such as the tree structure shown in FIG. 27 for re-writing or erasing part of the stored data. A directory record which identifies the file position is placed at an arbitrary position on the recording medium, as shown in FIG. 28 and as a result, a file may be recorded in a split form.
In a CD or in a video CD, a table-of-contents (TOC) area is provided at the leading end, or beginning portion, of the recording medium, and file position information is collectively recorded therein. Since audio data and video data are recorded continuously, normal and special reproduction (e.g., reverse play, fast play, etc.) likewise may be continuous. Such CDs and video CDs do not require a computer to recover data thereon, and thus, a dedicated reproducing apparatus, less expensive than a computer has been put to practical utilization. Nevertheless, as the processing ability of computers advances and as the cost of computing decreases, thereby making it feasible for a computer to handle audio data and video data, the usefulness of reproducing data recorded on a digital recording medium, such as a CD or a video CD, has been increasing.
However, when conventional computer techniques are used to reproduce data from a digital recording medium, such as a CD or a video CD, a dedicated program or file system must be recorded for the computer to recognize in order to reproduce the CD or the video CD, and a separate file needed for the file system, or a special computer program, must be disposed outside the area in which the continuous audio and picture data are recorded. As a result, the optical pickup for the recording medium is moved frequently to the separate computer program or file system, thus generally lowering the access speed of the optical disc drive.
Conversely, with a dedicated reproducing apparatus (i.e., not a computer or PC) for a medium in which data is recorded continuously, such as a CD player or a video CD player, it is difficult to operate with a recording medium on which the data has been recorded in a computer-compatible file system and thus possibly has been recorded discontinuously.